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How To Deal With Microbubbles In A Reef Tank!

Microbubbles really can be a pain for many people within the fish keeping hobby who keep a reef tank and they can totally ruin the viewing experience of your tank by clouding your water.

We have seen a wide range of questions from the community about how you should be dealing with microbubbles in a reef tank and there is a large amount of confusion out there on exactly what causes them too so we hope that our article will be able to help as many of our readers as possible.

There are some natural causes of microbubbles in reef tanks but these do tend to be rare and the majority of microbubbles are caused by the water and air mixing in the sump, drain line, or return line.

Many people overlook these potential causes of the microbubbles in their reef tank even though they are more common than the natural causes and are often much easier to fix.

If you notice that the microbubbles in your aquarium are usually sticking to your live rock rather than free floating in your tank then our article on why you have microbubbles on your live rock is probably worth reading.

There is a good chance that it is simply due to trapped air in your substrate escaping or a reaction between the minerals in your live rock causing excess air when touching the water.

What Are The Microbubbles In My Reef Tank

Microbubbles are tiny pockets of air that are usually created by aquarium accessories mixing air and water together due to the accessories not being set up correctly.

There are some natural causes of these air pockets in reef tanks but they are less common but are usually due to chemicals or minerals reacting with your water or due to certain types of algae blooms releasing large amounts of gas.

The vast majority of the microbubbles that can commonly occur in a reef tank are generic air and not made up of one single element and given time, they will often clear by themselves.

If the microbubbles in your aquarium are due to an algae bloom then the microbubbles will usually have a large concentration of oxygen in them rather than a mix of generic gas but this shouldn’t be much of a problem for most tank setups anyway.

If you are having problems with microbubbles that are originating in your substrate and you go out and get your own substrate instead of purchasing a commercial substrate product, the air bubbles may end up causing issues with your tank.

This is rare but they can quickly start to change your reef tanks water parameters so if you do notice that the microbubbles are emerging from your substrate then you should be testing your water parameters multiple times per day until they stop being created.

Why Do I Have Microbubbles In My Reef Tank?

The most common cause of microbubbles in a reef tank is due to the sump, drain line, or return line having problems allowing water and gas to mix resulting in a potentially large number of free-floating microbubbles in your reef tank.

Far less common causes of microbubbles in your reef tank include excess gas created by algae blooms, gas being released that was trapped in substrate, or reactions between minerals or chemicals with your aquarium water.

For some reason, the majority of the information online about having problems with microbubbles in your reef tank tends to look at potential causes of the bubbles outside of the sump, drain line, or return line.

In our opinion, this should always be the first place you check as they are by far the most common places that you are able to have problems where your aquarium water and gas can mix.

If you are new to reef tank keeping then you may be accidentally generating the microbubbles in your reef tank during your water changes by mixing water of different temperatures.

Colder water holds more oxygen than warmer water so adding colder water to your tank as part of your reef tank water change can temporarily release microbubbles as the water temperature normalizes but this should clear up in around a day.

How Do I Stop Microbubbles In My Reef Tank?

A quick visual inspection of your sump, drain line, and return line in your reef tank should be able to help you quickly identify any problem areas causing the microbubbles and help you fix the issue to stop them.

If you notice an algae bloom in your tank correlating with the microbubbles then dealing with the algae bloom should be able to prevent the microbubbles from consistently forming.

If you notice that the microbubbles are all emerging from your substrate after a recent substrate change then it is highly likely that the cause is either trapped air or a chemical reaction.

Both problems should be temporary, and the microbubbles should stop within a day or two of starting as the reaction stops or the trapped air makes its way to the surface.

As we touched on above, if your microbubbles are being generated due to a difference in temperature between your water during a water change, they should stop as the colder water reaches the same temperature as the warmer water.

In most cases, this can take as little as a few minutes with the microbubbles having cleared in around an hour but they can sometimes take as long as a day to fully clear depending on the tank setup.

Are Microbubbles Bad For Reef Tank Fish?

Microbubbles are usually not much of a problem for reef tank fish and they should not cause any long term problems even if there are a large number of bubbles in the tank.

In theory, microbubbles can technically warm the oxygen levels in the water in very rare situations but we have never seen any actual reports of this happening and causing problems with fish.

The most common reason that people get annoyed with microbubbles in their tanks is due to the bubbles reducing the visibility in their tanks and ruining their viewing pleasure.

As we covered earlier in the article, for the most part, most of the common causes of microbubbles in a reef tank are temporary and shouldn’t take too long to naturally dissipate anyway helping your water visibility return to normal.

We know that there are a number of posts on social media going over how microbubbles in an aquarium are bad for fish but like we mentioned above, this is usually based on a theory where it is technically possible but the realistic chances of it happening are extremely small.

Do Microbubbles Hurt Coral?

Microbubbles will rarely cause any serious problems for corals but in very rare situations, they can sometimes attach to corals and suffocate them.

You usually get plenty of warning on any issues as the corals will have a large number of the microbubbles stuck to them but this really isn’t common.

For the most part though, even sensitive corals should not have any real problems in a reef tank that is having problems with microbubbles.

Most corals can even have a surprisingly large number of microbubbles congregate on them with minimal issues too so for the majority of our readers, it is unlikely that you have anything serious to worry about.


That brings our article going over how to deal with microbubbles in a reef tank to an end. We hope that we have been able to help as many of our readers as possible who are having problems with microbubbles better understand the potential causes of the air pockets. Although each unique cause of microbubbles does have its own treatment, the majority of them will simply fade out over a day or two with all of the generated microbubbles having faded from the tank within a week so many people won’t have to actually do anything to treat the microbubbles in their tanks anyway.